Bisphenol A (BPA) is a common industrial chemical widely used to produce various plastics and is known to impair neural stem cells (NSCs). However, the effects of low-dose BPA exposure on the stemness maintenance and differentiation fate of NSCs remain unclear in the infant brain. The present study demonstrated that 1 µM BPA promoted human NSC proliferation and stemness, without significantly increasing apoptosis. The Chip-seq experiments demonstrated that both the cell cycle and the TGF-β signaling pathway were accelerated after treatment with 1 µM BPA. Subsequently, estrogen-related receptor α (ERRα) gene knockout cell lines were constructed using CRISPR/Cas9. Further western blotting and chromatin immunoprecipitation-PCR experiments demonstrated that BPA maintained cell stemness by binding to an EERα receptor and activating the TGF-β1 signaling pathway, including the downstream factors Aurora kinases B and Id2. In conclusion, the stemness of NSCs could be maintained by BPA at 1 µM through the activation of the ERRα and TGF-β1 signaling pathways and could restrain the differentiation of NSCs into neurons. The present research further clarified the mechanism of BPA toxicity on NSCs from the novel perspective of ERRα and TGF-β1 signaling pathways regulated by BPA and provided insights into potential novel methods of prevention and therapy for neurogenic diseases.

Background: Methylmercury (MeHg), manganese ions (Mn 2+ ), and lead ions (Pb 2+ ) are ubiquitous environmental pollutants and may be neurotoxic especially during fetal development. We decided to explore the toxic mechanisms of MeHg (organic heavy metals), Mn 2+ (inorganic heavy metals) and Mn 2+ on the proliferation and differentiation of human neural stem cells (hNSCs). Materials and Methods: The proliferation and apoptosis of hNSCs were analyzed via CCK-8 method and flow cytometry under MeHg, Mn 2+ and Pb 2+ , respectively. RNA-seq was used for analyzing proliferation/differentiation mechanism of MeHg, Mn 2+ and Pb 2+ stressing hNSCs. Results: Our experiment found that when hNSCs were exposed to below 0.5 nM MeHg, 5μM Mn 2+ and 10 μM Pb 2+ , cell proliferation and differentiation were promoted. Apoptosis rates increased significantly when hNSCS were exposed to exceed 0.5 nM MeHg, 5μM Mn 2+ and 10 μM Pb 2+ . RNA-seq results showed that metal ions altered the genes expression level and signaling pathways of hNSC differentiation and proliferation, but the regulatory mechanisms of MeHg, Mn 2+ and Pb 2+ were different. Conclusion: Our findings indicated that very low-dose metal exposure may deplete hNSC pool by making prematurely differentiated neurons increase, which may be the real cause of long-term nervous system disruption in adulthood, rather than higher metal doses will cause more direct toxicity during infant development.